An electrical distribution system typically includes distribution lines or feeders that extend out from a substation transformer. The substation transformer is typically connected to a generator via electrical transmission lines.
Along the path of a feeder, one or more distribution transformers may be provided to further step down the distribution voltage for a commercial or residential customer. The distribution voltage range may be from 5 through 46 kV, for example. Various connectors are used throughout the distribution system. In particular, the primary side of a distribution transformer typically includes a transformer bushing to which a bushing insert is connected. In turn, an elbow connector, for example, may be removably coupled to the bushing insert. The distribution feeder is also fixed to the other end of the elbow connector. Of course, other types of connectors are also used in a typical electrical power distribution system. For example, the connectors may be considered as including other types of removable connectors, as well as fixed splices and terminations. Large commercial users may also have a need for such high voltage connectors.
One particular difficulty with conventional elbow connectors is that they use curable materials. For example, such a connector may typically be manufactured by molding the inner semiconductive layer first, then the outer semiconductive jacket (or vise-versa). These two components are placed in a final insulation press and then insulation layer is injected between these two semiconductive layers. Accordingly, the manufacturing time is relatively long, as the materials need to be allowed to cure during manufacturing. In addition, the conventional EPDM materials used for such elbow connectors and their associated bushing inserts may have other shortcomings as well.
One particularly advantageous elbow connector configuration which addresses many of these shortcomings is disclosed in U.S. Pat. Pub. No. 2004/0102091 to Jazowski et al., which is assigned to the present Assignee. This application discloses an elbow connector including a connector body having a passageway therethrough. The connector body includes a first thermoplastic elastomer (TPE) layer adjacent the passageway, a second TPE layer surrounding the first layer and comprising an insulative material, and a third TPE layer surrounding the second layer. The TPE material layers may be overmolded to thereby increase production speed and efficiency and lower production costs. The TPE material may also provide excellent electrical performance and other advantages as well.
Despite such advancements in fabrication, typical elbow connectors may experience other shortcomings with respect to installation. More particularly, an elbow connector includes first and second interconnecting passageways. A conductive member having a threaded opening is positioned in the first passageway so that the threaded opening is accessible via the second passageway. A loadbreak probe is inserted into the second passageway and has a threaded end to be threaded into the opening of the conductive member to provide an electrical (as well as mechanical) connection therewith.
The threaded end portion of an exemplary prior art loadbreak probe 100 is illustrated in FIG. 6. The probe 100 illustratively includes a cylindrical body 101 and a threaded end including a shaft 102 extending from the body. The shaft 102 has a constant diameter d along an entire length l thereof, and threads 103 extend along the shaft from the body 101 to about three-quarters of the length up the shaft, leaving an unthreaded tip 104. One drawback of this arrangement is that when installers insert the probe 100 into the second passageway of the elbow connector, they may have difficulty seeing the internally threaded opening of the conductive member and the threaded end of the probe. Further, the conductive member can get turned within the first passageway so that the threaded opening is not properly aligned with the second passageway. Thus, it is quite possible for an installer to have difficulty aligning the probe with the threaded opening of the electrode. As a result, cross-threading may occur, and thus upon tightening the probe with a probe tightening tool the threads of the opening and/or the probe may be damaged. If detected, this requires replacement, and, if undetected, may result in premature failure.